A DFT study of DMC formation on Rh‐doped Cu/AC surfaces

The activity and selectivity of heterogeneous catalysts can be significantly improved by dispersion of another active component in the metal substrate. The impact of Rh promoter on the formation of dimethyl carbonate (DMC) via oxidative carbonylation of methanol on Cu–Rh/AC (activated carbon) catalyst was investigated by density functional theory calculations. The most stable configurations of reacting species (CO, OH, CH₃O, monomethyl carbonate, and DMC) adsorbed on the Cu⁰(zero‐valent copper)/AC and Cu–Rh/AC surfaces were determined on the basis of the calculated results. The reaction energy and activation energy of the rate‐limiting steps on the Cu–Rh/AC and Cu⁰/AC surfaces were compared. The activation energies of the rate‐limiting step of CO insertion into dimethoxide are 206.3 and 304.8 kJ mol^?1 on the Cu–Rh/AC and Cu⁰/AC surfaces, respectively. The activation energies of the rate‐limiting step of CO insertion into methoxide are 78.5 and 92.7 kJ/mol on the Cu–Rh/AC and Cu⁰/AC surfaces, respectively. The calculated results indicate that the addition of Rh atom has a significant effect on decreasing the active energy the main pathway for DMC formation. © 2015 Wiley Periodicals, Inc.     

新型核素~(64)Cu标记硝基咪唑类肿瘤乏氧显像剂及正电子发射断层扫描显像研究

采用新型核素64Cu标记了含丙烯胺肟[Pn AO(3,3,9,9-Tetramethyl-4,8-diazaundecane-2,10-dione Dioxime)]结构的硝基咪唑类乏氧显像剂Pn AO-1-(2-nitroimidazole)[BMS181321],通过优化反应条件,于室温下反应10 min后即得到高放化纯度和高比活度的标记化合物64Cu-BMS181321.目标产物经放射性高效液相色谱检测验证和体外稳定性实验确认后,通过尾静脉注射到人源胰腺癌(PANC-1细胞系)裸鼠体内,分别于注射显像剂4和8 h后进行小动物正电子发射断层扫描显像(Micro-PET).结果表明,4 h左右肿瘤乏氧区域有良好的放射性浓聚.64Cu-BMS181321的合成及其分子显像研究开创了64Cu标记硝基咪唑类乏氧显像剂进行乏氧显像的先例,经进一步药物临床实验评价后,64Cu-BMS181321有望成为具有良好前景的PET乏氧显像药物.     

改性活性炭纤维可见光催化联合脱硫脱硝的研究

利用水合肼还原法制备的TiO₂/Cu₂O复合光催化剂对活性炭纤维(ACF)进行改性,利用SEM、XPS、BET以及XRD对其进行表征,研究改性后ACF的性质及其脱硫脱硝效果。研究表明,TiO₂/Cu₂O同时改性后的ACF表面孔径减小,但表面石墨碳和羰基(C=O)官能团增加,增强了ACF对NO和SO₂的吸附能力,从而提高了脱硫脱硝的效率,该催化剂在40℃、可见光的催化下脱硫效率达90%,脱硝效率达60%。     

Synthesis of organosilyl compounds-containing 1,2,4,5-tetraaryl imidazoles sonocatalyzed by M/SAPO-34 (M = Fe,Co, Mn,and Cu) nanostructures

The one-step synthesis of silylated 1,2,4,5-tetraaryl imidazoles by use of a series of M/SAPO-34 (M: Fe, Co, Mn, and Cu) nanocatalysts and subsequent silylation reactions is described. Cu/SAPO-34 catalyst has the highest activity in improving the efficiency of the heterogeneous cyclo-condensation of an aldehyde, benzil, ammonium acetate and a primary aromatic amine in water under ultrasonic irradiation. Some of imidazole derivatives are studied with a view to the synthesis of a series of new, multi-substituted imidazoles containing organosilyl groups including carbosilanes (Si–C) and silyl ethers (Si–O).     

咔唑-二氨基马来腈类荧光探针的合成及对Cu2+和ClO-的检测

利用咔唑醛与二氨基马来腈合成了一种对Cu²⁺和ClO^-的响应的荧光探针分子CMN。探针分子与Cu²⁺作用后,紫外吸收光谱在394 nm处的吸光度迅速下降,颜色由黄色褪至无色;荧光光谱在452 nm处的发射峰迅速增强,出现明显的蓝色荧光。探针与ClO^-作用后,溶液发生褪色,并在375 nm和394 nm出现强荧光发射,发出淡蓝色荧光。CMN通过配位过程实现了对Cu²⁺的检测,其检测限为47μmol/L;CMN在ClO^-催化下亚胺键水解得到咔唑醛,实现了对ClO^-的检测,检测限3.06μmol/L。CMN可作为荧光检测试纸快速检测环境中的Cu²⁺和ClO^-。     

氮掺杂碳原位锚定铜纳米颗粒用于高效氧还原反应催化剂

与贵金属铂基电化学氧还原反应（ORR）催化剂相比,廉价的非贵金属催化剂引起了广泛的关注。本文以壳聚糖作为一种富含氮和碳元素的生物质资源,利用碳浴法成功制备了氮掺杂碳原位负载铜纳米颗粒（Cu/N-C）催化剂。纯壳聚糖碳化得到的样品N-C的比表面积为67.5 m²·g^-1、平均孔径0.14 nm、平均孔体积8.00 m²·g^-1,与之相比,Cu/N-C比表面积可达607.3 m²·g^-1、平均孔径为2.5 nm、平均孔体积为0.40 cm³·g^-1。通过密度泛函理论（DFT）进行计算表明,Cu(111)/N-C的自由能值低于N-C,更有利于氧还原催化进行。在0.1 mol·L^-1 KOH的介质中,Cu/N-C不仅表现出优异的起始和半波电势（分别为0.96 V和0.84 V）,而且还表现出了优异的抗甲醇性能和稳定性,并且Cu元素掺杂量达到1.67wt.%。     

Copper Nanoparticles In鄄Situ Anchored on Nitrogen鄄Doped Carbon for High鄄Efficiency Oxygen Reduction Reaction Electrocatalyst北大核心CSCD

Compared with noble metal platinum (Pt)-based catalysts, inexpensive non-noble metal electrocatalysts have attracted extensive attention for oxygen reduction reaction (ORR). Herein, chitosan as a kind of biomass resource rich in nitrogen and carbon was used to prepare nitrogen-doped carbon (N-C) and N-C in-situ anchored by copper nanoparticles (Cu/N-C). The as-obtained N-C and Cu/N-C nanoparticles were successfully used as non-noble eletrocatalysts tested for ORR. Compared with the N-C, the Cu/N-C showed the high surface area of 607.3 m2窑g-1 with the mean pore size of 2.5 nm and the pore volume of 0.40 cm3窑g-1. The most positive Gibbs free energy change was the rate determining step for ORR process with the 4e mechanism, where the value of the Cu (111)/N-C(-0.39 eV) was lower than that of the N-C(-0.26 eV). The Cu/N-C exhibited superior onset and half-wave potentials (0.96 V and 0.84 V, respectively) in alkaline media (0.1 mol窑L-1 KOH), all of which are much better than those measured for N-C and commercial Pt/C. Furthermore, the Cu/N-C showed superior methanol crossover avoidance and oxygen reduction stability. © 2021 Authors. All rights reserved.     

Cu2O/CuO Electrocatalyst for Electrochemical Reduction of Carbon Dioxide to Methanol

Herein, we report the controlled and direct fabrication of Cu₂O/CuO thin film on the conductive nickel foam using electrodeposition route for the electrochemical reduction of carbon dioxide (CO₂) to methanol. The electrocatalytic reduction was performed in CO₂ saturated aqueous solution consisting of KHCO₃, pyridine and HCl at room temperature. CO₂ reduction was carried out at a constant potential of −1.3 V for 120 min to study the electrochemical performance of the prepared electrocatalysts. Cu₂O/CuO shows better electrocatalytic activity with highest current density of 46 mA/cm². The prepared catalyst can be an efficient and selective electrode for the production of methanol.     

Facile Synthesis of Cuprous Oxide/Gold Nanocomposites for Nonenzymatic Amperometric Sensing of Hydrogen Peroxide

In this work, a facile preparation method of cuprous oxide/gold (Cu₂O/Au) nanocomposite was successfully developed. The process consisted of one‐pot co‐reduction of HAuCl₄ and CuSO₄ using ascorbic acid (AA) as a reducing agent at room temperature under magnetic stirring. The structures and compositions of the as‐prepared products were characterized by SEM, EDS, and XRD. Cyclic voltammetry and chronopotentiometry studies revealed that the as‐prepared cubic Cu₂O/Au nanocomposites showed enhanced performance towards the non‐enzymatic catalytic reduction of hydrogen peroxide (H₂O₂) when compared to single‐component Cu₂O nanocubes. The linear range of H₂O₂ determination spanned over 4 orders of magnitude (1 μM∼16.7 mM) and the detection limit was low as 0.45 μM (S/N=3). The enhanced performance of cubic Cu₂O/Au was attributed to: i) the synergistic effect between Cu₂O and Au, ii) the increase in surface area induced by the reduced size of the nanocubes, and iii) the improved electrical conductivity due to the presence of Au in the particles. Overall, the cubic Cu₂O/Au nanocomposites prepared by the proposed method hold great promise for future practical use in H₂O₂ detection.     

Two-step polymerization approach for synthesis of macroporous surface ion-imprinted cryogels

Today, the surface imprinted polymers emerge in various fields as synthetic adsorbents gaining attention in a variety of application areas. In this study, Cu(II) ion surface imprinted poly(2-hydroxyethyl methacrylate-glycidyl methacrylate), poly(HEMA-GMA), cryogels were synthesized via modified two-step polymerization which is different from given in literature and the adsorption of Cu(II) ion from aqueous solution was investigated batch wise. In this respect, the method applied in this study is new in the literature despite heavy metal removal studies reported. The polyethyleneimine (PEI) molecule was used in polymeric structure as a ligand. The poly(HEMA-GMA) cryogels prepared was characterized via Fourier transform infrared spectroscopy (FTIR), inductively coupled plasma optical emission spectrometry (ICP-OES), elemental analysis, scanning electron microscopy (SEM) and the micro-computed tomography (μCT).